A tunneling/cache thread, with night ops in mind. A hiding place for gear, plans, and *cough other stuff. Anything from a hole in the ground to a makeshift shelter, would be very useful. Would this be a viable project? Any resources would be welcome.

I've done this before while staying at another house, just hid all my opping kit in the garage in a bag behind an old toolbox. You probably don't need to invest in decent security unless the gear you're carrying is highly illegal/suspicious for your area. Heck, you can probably hide your gear in plain sight. Dark clothing cam be mixed with your regular wardrobe, balaclavas & masks can be hidden amongst scarves, beanies and other headgear, B&E tools can be mixed in with other tools in the garage, you can hide your knife & other supplies with camping gear, etc. Less suspicious than having all that in one place.

We are all books containing thousands of pages and within each lies an irreparable truth.
What is locked, can be opened. What is hidden, can be found. What is yours... can be mine.

If you owned property the fastest and cheapest way to go about it would be to get an old scrapped bus and bury it with the ass out in the open like a cold war shelter or some other similar option, but why would you want to for something like this? In night ops you don't need such an elaborate set up. For other things, sure, but that's outside the scope of the site I'd say.

There is a difference between those who feel safest in the light and those who feel safest in the dark.